What is a mixture of gasoline and ethanol called?

A mixture of gasoline and ethanol is called gasohol.

Gasohol is a general name for motor fuel made by blending gasoline with ethanol, an alcohol commonly produced from crops such as corn or sugarcane. The best-known modern example is E10, which contains 10% ethanol and 90% gasoline by volume. Fuel labels such as E5, E15, and E85 identify the approximate ethanol percentage.

Ethanol is added partly because it is a renewable fuel and can raise gasoline's octane rating, helping resist engine knocking. It also contains oxygen, which can support more complete combustion. However, ethanol has less energy per gallon than gasoline, so higher-ethanol blends can slightly reduce fuel economy.

Gasohol is not the name of one fixed formula: its exact composition depends on the blend and local fuel standards. Most ordinary cars are designed to use low-level blends such as E10, while E85 requires specially designed flex-fuel vehicles. Gasoline and ethanol can also absorb water, which is why fuel storage and handling matter, especially in older engines and small machines.